Occlusive vascular disease is generally characterized by a hardened, calcified deposit blocking the flow of blood through a blood vessel. Occlusive vascular disease can cause blockages in both coronary and peripheral blood vessels. Particularly serious examples include situations in which the lesion and deposit completely block the vessel, a condition known as chronic total occlusion (CTO). A typical CTO is a lesion located in a blood vessel of a patient that results from an accumulation of deposits, typically calcified fibrin.
Traditionally, treatment of this type of disease has required an invasive and traumatic surgical bypass of the blocked vessel. More recently, considerable effort has been invested in treating occlusive vascular disease by advancing a guidewire through or across the diseased location to create a passageway for various types of interventional procedures, including percutaneous transluminal coronary angioplasty (PTCA), atherectomy, stent delivery, and other catheter-based treatments.
Often, the true lumen of the vessel is embedded in the occlusion and is surrounded by false lumens that have been created over time. Attempts to cross the true lumen can result in the tip of the guidewire being deflected by the false lumens or off the hard cap of the occlusion into the subintimal area between the intimal layer and the adventitial layer of the blood vessel. Alternatively, a device may be deliberately guided into the subintimal area to bypass the lesion, avoiding the difficulties associated with penetrating the occlusion. Such techniques can also potentially result in a smoother passageway.
However, once the device is in the subintimal area, it can be very difficult to direct the device back into the blood vessel lumen. Currently preferred methods for these procedures involve the use of a catheter having a deflection function configured to steer the guidewire or another device back into the true lumen of the vessel. Such catheters are generally termed “re-entry” catheters.
A number of challenges are associated with the design of re-entry catheters. For example, the tip of the catheter should be held in an appropriate rotational orientation so that a passageway can be formed back into the true lumen. Further, even if most of the lesion has been bypassed, it is still often necessary to penetrate some portion of the occlusion. As a result, the re-entry catheter should minimize the difficulties in forming a passageway through a hardened lesion. Another important characteristic is the trackability and flexibility of the device. To navigate the tortuous vasculature, the device must be sufficiently flexible to allow traversal of relatively tight bends and twists. However, it is also beneficial to provide sufficient stiffness to improve the pushability of the device and to transmit torque applied to a proximal end of the device to the distal tip.
Therefore, a need remains for a medical device that can be easily positioned relative to a lesion occluding a vessel to facilitate the creation of a passageway into the true lumen from a subintimal area. It would be advantageous to provide such a device with the flexibility to be advanced through the vasculature. It would also be advantageous to provide a means to stabilize and support the device while the passageway into the true lumen is formed. As will be detailed in the discussion follows, this invention satisfies these and other goals.